1. Field of the Invention
This invention relates to the field of slot array antennas and more particularly to lightweight armored antennas having high structural strength for use in battlefield environments.
2. Description of the Prior Art
Slot array antennas have been used for radar applications for many years. The slot array antennas generally comprise multiple parallel rows of waveguides having slots in the waveguide walls that face the direction of radiation, structural supports for the waveguides, a radome to weatherize the antenna, and a pedestal to support and rotate the antenna assembly. The antenna assembly generally has a small depth, but a relatively large surface area.
The use of antennas of this type on seagoing vessels presents unique problems. The antenna usually must be situated high on a mast where it is highly exposed to enemy fire and explosive detonations (nuclear and conventional) from all aspect angles. Weight is a highly critical factor, especially since weight above the waterline must be ballasted with greater weights below the waterline to maintain ship stability. Every pound of the antenna must usually be ballasted with about ten pounds below deck. Armoring the antenna and strengthening the structure of the broad, thin antenna panel to allow it to survive flak and the blast effects of explosives adds much weight which will slow the ship. Present antenna designs generally utilize a riveted monocoque structure supporting the array of slotted waveguides and their sinuous feed with ribs, intercostals, a polyester fiberglass radome, and various supplementary pieces. A backbone casting is located behind the monocoque antenna structure, providing the structural interface between the antenna and the pedestal. Conditioning the antenna against the thermal pulse of a nuclear explosion requires the addition of heat resistant dielectric material.
It would be desirable to find a way to reduce the weight of the antenna without increasing its susceptibility to damage from blast and thermal pulses, and it is the solution to this problem to which the present invention is directed.